While many types of radio signal transmitters and receivers have been used to signal the presence of a person or object, no patent appeared to set forth a system such as described herein. Patents uncovered which relate to the field are the following: U.S. Pat. Nos. 4,403,341; 4,430,757; 4,121,160; 3,163,856; 4,110,741; 4,359,723; 3,806,936; 3,336,530; and 3,243,812.